The present invention concerns a pneumatic brake booster capable of operating without being actuated by a pedal, and possessing at least one fixed part and a control rod with which the pedal cooperates.
Such a brake booster finds a preferred application in the boosting of the braking of motor vehicles fitted with a device allowing the slowing down of a driven wheel tending to spin on the running surface or with a device for automatic braking in response to a signal emitted, for example, by a beacon or a radar.
Such a brake-booster is, for example, described in EP-A-0 303 470, and its operation, well known to a person skilled in the art, will not be described in detail here.
The brake-booster from this document possesses one grave disadvantage in that, during its operation in automatic mode, the brake pedal is moved by the control rod as if it had been actuated by the driver. Because of this, if the driver wishes at that moment to press on this pedal himself, he fails to find it in its usual place, which may result in a moment of panic detrimental to good driving. In addition, in the automatic operating mode, the pedal being depressed, it becomes impossible to detect the fact that the driver himself wishes to brake, which may have grave consequences, especially if the brake booster is used with an anti-wheelspin device. The present invention has the object of preventing these disadvantages.